Two Grand Canyon-size valleys on far side of the moon formed within 10 minutes | Hacker News Reader

Two Grand Canyon-size valleys on far side of the moon formed within 10 minutes

cnn.com

91 pointspseudolus73 comments

   Then, the ejected debris that created the canyons likely soared over the lunar surface and then collided with it at speeds of about 2,237 miles per hour (3,600 kilometers per hour).

Oddly adding a veil of precision to an estimate of a kilometre per second.

Yeah, they just did the conversion and slapped it on there. Should have said "about 2200 mph".

It's unfortunate that the only written mechanism we have for expressing a lack of precision is scientific notation, which tends to be obfuscating for numbers at this scale: if you write "3.6e3 kph (2.2e3 mph)", you make it clear approximately how much precision you do and don't have, but it's less obvious-at-a-glance for the target audience of an article like this.

Or use kps and not lose additional precision every time you translate units?

In an ideal world.

m/s

Or that, anything SI

2200 would improperly add an extra significant figure, "about 2000" would be okay.

I had figured since km/h was NN00, the same would be good for mph.

Naw, it's already been false precisioned to hell.

The original would have been "about 1000 metres/second". That got translated to 3600 km/h etc.

Check how much it charges if it was really 800 m/s. Or 1200 m/s.

That's only a problem if your favorite method of representing uncertainty is in-band signalling via a technique like significant figures.

You could translate the units and then also translate separately the error bands (assuming +/- 100 km). But “2237 mi/hr +- 62 mph” sounds pretty silly.

Use the error bands to find a close-enough round number: 2200 or 2300 mph or "almost 3 times the speed of sound on earth"

Anyone pedantic enough to notice the conversion mismatch should be smart enough to understand the concept of "error bars".

10 m/s = 36 km/h, I believe they started from a round number.

US people typically want numbers translated into American football fields it seems. So around 39,000 football fields an hour might be more obvious.

Please be complete if you’re gonna translate to American units. That’s 117,000 football fields per football game, or 325 per commercial.

Does the hour include or exclude ad breaks?

That's nothing! They determined that one valley formed 3.8 billion years ago, and the other one, 3.8 billion years plus or minus 10 minutes.

> That's nothing! They determined that one valley formed 3.8 billion years ago, and the other one, 3.8 billion years plus or minus 10 minutes.

Now that's what i call precision. How did they measured it ? With a pendulum ? /s

Its because they started with "roughly 1km/s", which was deemed too difficult to understand for pleb readers, so it was converted to km/h, which is more relatable. Then it was converted to mph for the US audience, and the author just did a straight conversion without really considering the madness that is " about 2237 mph". I hate it when they do this.

1-2km/s, which is a reasonably accurate estimate for these things, should have been translated to "2000-4000mph" and it would have been perfectly good enough.

extremely misleading headline implies that it just happened.

No it doesn’t. English is as algorithmic as math.

If there is a formula x = x^1 + y you wouldn’t say ; no good it implies z is also the same. You would not because it says nothing about z.

If you have a specification for a program saying "input: variables x and y, output: z holds x+y", you would probably be annoyed if someone coded "x=0; y=0; z=0", though.

Just playing devil's advocate, I think the headline is not bad (could be less ambiguous, but sacrificing brevity)

Figured someone would have to get specific. Lol.

Have you read The Overstory? I recommend it, it’s a great modern novel.

“What they do?”

> English is as algorithmic as math

Ain't no way!

This "illogical" double negative shows how English is not at all like algebra. English is not a set of formal rules - there is no formal authority on the language. The rules that exist are derived from how English is commonly used - descriptive rather than prescriptive. This is why dictionaries are constantly adding new (sometimes annoying) words, and the Chicago Manual of Style is on its 18th version. For example, I was taught that "they" could never describe a singular person, and one should assume "he", "she" or "the suspect". Not so anymore [1]. The language, its constructs, and implicit rules are always changing, regardless (and irregardless[2]) of how you criticize those that speak it.

[1] https://www.chicagomanualofstyle.org/help-tools/what-s-new.h... [2] https://dictionary.cambridge.org/us/dictionary/english/irreg...

Yeah I could say:

"Wall Street Loses 14% Within 10 Minutes of Opening Bell" (1929 Crash)

"Radio Broadcast Causes Mass Panic Within 10 Minutes" (1938 War of the Worlds)

You're somewhat exaggerating the effect, the headline uses past tense and your comparisons don't.

Misleading? Or just misintepretable? Misleading implies the author tries to lead you to a wrong conclusion. The article is very clear about what it really means.

I immediately read the headline as "it happened in a time span of 10 minutes probably a gazillion years ago". So in any case, it's not misleading to everyone, and therefore certainly not "extremely misleading".

> Misleading implies the author tries to lead you to a wrong conclusion.

Why on earth would anyone assume that this clickbait title wasn't intended to be clickbait? What history of non-clickbait headlines would make anyone assume good faith on the part of CNN here?

Just because someone makes a wrong assumption about a headline doesn't mean they have to come here and tell everyone else about it.

It is missing a verb: “were” formed

Reading is an act of guessing. I guessed that if the moon had recently been impacted that hard we would be hearing about it from more than CNN, and likely would have known about it in advance. I don't feel as though I have been mislead.

Funnily enough I went to the article because I guessed that it would have literally formed overnight by some surface movement originating from within the moon not some external cause. And I believe my guess is as good as yours except in hindsight of course.

Neal Stephenson fans are already heading to the salt mines.

Seveneves in case anyone wants to read it. I thought it was okay, certainly captivating enough for me to finish it.

I thought it was quite good, although maybe it should have been a series rather than a single book. That might have given Stephenson time to flesh out the end, which felt a bit rushed.

A rushed ending seems to be a key Stephenson trait in my experience haha

To call that ending a bit rushed might be a little generous.

It is impossible for a headline to give you all of the details of an article.

If you feel “tricked” into reading an astrogeology article, I would suggest you might be one of the people who should be reading it.

> astrogeology

English needs a better term for this field. I understand that Astrology is already taken, but astro- (stars) geo- (earth) logy (study) is just wrong.

Maybe Exolithology? Or Lunology, if these processes are unique to smaller bodies. Actually, our moon does have a differentiated core (I think the only one in the solar system) so per that argument we're a double planet (also the fact that the moon never has retrograde motion relative to the sun, another unique feature of our moon in the solar system) and thus just Geology is a proper enough name.

No one said they were "tricked" by the article, only that the found the headline to be misleading which is entirely fair because it is a clear example of clickbait.

It didn't imply that. You inferred that. Big difference.

>The energy unleashed that created the canyons was 1,200 to 2,200 times more powerful than the nuclear explosion energy once planned to excavate a second Panama Canal, the study authors estimate.

Sometimes I miss that crazy boldness of the beginning of the Cold war era - imagination, engineering prowess and just a sprinkle of pure insanity.

If it wasn't for the radioactive fallout, it wouldn't have been a bad idea. It took time to understand how bad the fallout was. And perhaps ultimately, we came to an overestimate of how bad it is for various reasons... people are generally unaware that about 500 surface nuclear bombs have been set off for testing, and I think a lot of people would think that that is already enough to render Earth uninhabitable or something. (Although over the course of decades, not all in one construction project.) From a strictly rational perspective it is probably something that could be done reasonably, but, the world is what it is.

The tests are very pretty to watch though. I'm very grateful they were recorded.

Even without the fallout you're still looking at a nuclear winter just from blowing all of that rock dust into the atmosphere.

I think that you don't have fallout. You dig charges deep, the goal is to make huge caverns that you collapse and are filled with water? This is how I would do it anyway.

Rock is not very compressible. The cavities created by underground nuclear tests aren't that large: https://en.wikipedia.org/wiki/Underground_nuclear_weapons_te... . They did get surface subsidence, but maxing out at a scale of "over half a mile", and not terribly deep. To create "huge caverns", that volume still has to go somewhere, and when you're talking about vaporized rock that mostly means atmosphere or nothing, more often the latter. But at least they didn't always get fallout, that's nice.

Like Aral Sea? Thanks, I can live without.

When men were men, and test pilots were dropping like flies . . .

These comparison units are crazy. Normal people don't know how much energy was proposed for the Panama Canal thing either.

ha! True.

Yeah, back then the insane ideas were pushing the limits on unbounded possibilities (including unbounded destruction).

Now the insane ideas are on how to deal with our bounded resources and life support systems (or pretending such bounds don't exist...)

Whatever, but that's the weirdest unit of measurement I ever read.

less clickbait title would begin with: "millions of years ago..."

Billions

Billions is technically also millions… not the parent commenter, just thought I’d be a nit

By that logic, you can also say seconds ago...

"10^17 seconds ago..."

This is why my go-to estimate for many things where the result is outlandishly large is "at least six".

> “Nearly four billion years ago, an asteroid or comet flew over the lunar south pole, brushed by the mountain summits of Malapert and Mouton, and hit the lunar surface,” Kring said. “The impact ejected high-energy streams of rock that carved two canyons … in less than 10 minutes.”

For comparison, it took 5 million to 6 million years for water to erode the landscape of Arizona to create the Grand Canyon.

Well yeah, it sounds perfectly reasonable that two wildly different mechanisms of producing a crack in the surface of a celestial body would also work on wildly different timescales. I mean, the crater itself (which is even bigger than the "canyons") also formed within 10 minutes or less, but that doesn't sound so spectacular, because all impact craters are formed this way.

From the Nature article[1], despite being prominent in the abstract it's almost a throwaway in the body:

> ... Moon’s Vallis Schrödinger and Vallis Planck were carved by streams of impacting rock in less than 10 min.

and earlier in the same article:

> Flight times of debris producing the 270 km-long main canyon are 4.9 to 15.0 min for Vallis Schrödinger over the entire range of potential ejection angles, with canyon-forming secondary impacts occurring within a 5 min interval. Flight times of debris producing the 280 km-long main canyon are 5.2 to 15.4 min for Vallis Planck over the entire range of potential ejection angles, with canyon-forming secondary impacts occurring within a 5 min interval.

I didn't dig all the way into how we get 10 minutes from 4.9-15 minutes. I was very interested in how this time was so confidently bounded. I'm guessing it's the graph that charts impact sizes, distances, and energies to assume flight travel time from a point of impact.

I'm also annoyed at the shift from "min" to "minutes" during the article. That just seems like really bad editing.

[1] https://www.nature.com/articles/s41467-024-55675-z

It would be really cool if they explained why the erosion was so concentrated in those two particular directions, instead of generally peeling back the surface or even lots of smaller streams in all directions. Why the asymmetry?

Large pieces of debris, I’d assume.

I guess a very shallow angle of impact was part of it:

> brushed by the mountain summits of Malapert and Mouton

(3.8 billion BC)

Touché

BC? 3.8 billion + 2024 is still just 3.8 billion.

My comment is meant to be humorous (while still being informative) because the title is misleading.

But 3.8 billion A.D. is far in the future.

"BC" is shorter than "ago"

“…giant backhoes that have dug up the lunar surface and exposed material from underneath…”

That’s indeed compelling to get rock samples from.

Maybe it would be even possible to see different layers of moon inside those canyons, but afaik the whole moon is covered in dust isn’t it?

So what. I used to bullseye womp rats in my T-16 back home. They're not much bigger than two meters.

Schrödinger impact basin…mmmmm

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